NullPointerException occuring after null check java

Question

I have this if statement

if((check1==null||!check1.isSolid())&&(check2==null)||!check2.isSolid())

it throws a null pointer exception because check1 or check2 are null, but i don't understand why it is doing this, because i am checking for the null condition before i am accessing the object and if the object is null why would java bother checking isSolid because it would have already been true.

Answer 1

Your messed up your parenthesis. Java will group your statement together like this:

((check1 == null || !check1.isSolid()) && check2 == null) || !check2.isSolid()

If check1 is null and check2, is null, the first statement will evaluate to true. The problem occurs when your move on to the second statement, since check2 is null, check2.isSolid() will through a NullPointerException.

Change your parenthesis to

(check1 == null || !check1.isSolid()) && (check2 == null || !check2.isSolid())

Answer 2

You mixed up the parentheses. Try:

if((check1==null||!check1.isSolid())&&(check2==null||!check2.isSolid()))

Answer 3

Try this:

boolean check1_result = (check1 == null) ? true : !check1.isSolid();
boolean check2_result = (check2 == null) ? true : !check2.isSolid();

if (check1_result && check2_result)
// do work...